Strontium narrow-line spectroscopy at 689 nm in a microfabricated vapor cell

Alkaline earth-like atoms such as Sr and Yb atoms are widely used in quantum sensing and quantum computing. For example, they are the workhorses in the state-of-the-art optical lattice clocks and some neutral atom quantum computing platforms. These cold-atom experiments rely on bulky and expensive hollow cathode lamps and optical cavities to stabilize the cooling laser frequencies. Here we report a linewidth below 200 kHz for the 689 nm intercombination line in a microfabricated thermal Sr vapor cell. This could provide an alternate method for cold-atom experiments to lock the frequencies of cooling laser that is compact, low-cost, and manufacturable. Furthermore, these 100 kHz transitions in microfabricated vapor cells are promising candidates to build the next-generation compact optical atomic clocks with performance similar to a hydrogen maser. We discuss the cell fabrication process, shelving spectroscopy setup, and the linewidth contributions from transit time, residual gas collisions and probe laser power.